The Theory of the Ball Hog: Studying Strategic Cooperation through Sport

Chelsea GarberRoyce Sport and Society Fellowship

Project Motivation• Economics– Game theory (Behavioral economics)– Individual decision-making– “Strategic interaction” – Incentives to cooperate?

• Sports– Power of the observer– Unique lens– Supposed common goal among cooperating

teammates– Rugby production function

Game theory in economic practice• Classic example: Prisoner’s Dilemma

Rugby Data• WRWC 2010– Statistics on many aspects of the game– Surprisingly subjective and difficult, in part due

rugby fast-paced and continuous nature– Needed a proxy for “cooperation”– Detailed passing data

Mathematical Application• “Betweenness centrality” algorithm• Rank player contributions

Rugby Background• Elusive rugby production function– Players specialize– Primary distributors: scrumhalf and flyhalf– Primary play-makers: flyhalf and fullback

• Benefits of Cooperation– Do you really want your best player to pass?

Passing Network: New Zealand

Passing Network: England

FindingsFirst Place – New Zealand Second Place –England

1. Scrumhalf2. Flyhalf3. Fullback4. 8 man5. Tighthead prop6. Outside center7. Inside center8. Wing9. Hooker10. Wing11. Second row12. Open flanker13. Second row14. Loosehead prop15. Closed flanker

1. Scrumhalf2. Flyhalf3. Fullback4. Outside center5. Wing6. Inside center7. Wing8. Loosehead prop9. Open flanker10. Hooker11. Second row12. Tighthead prop13. Closed flanker14. Second row15. 8 man

Findings, continuedThird Place – Australia Fifth Place - USA

1. Flyhalf2. Scrumhalf3. Fullback4. Wing5. Inside center6. Open flanker7. Wing8. Second row9. Second row10. Loosehead prop11. Hooker12. 8 man13. Closed flanker14. Outside center15. Tighthead prop

1. Outside center2. 8 man3. Scrumhalf4. Fullback5. Wing6. Wing7. Inside center8. Tighthead prop9. Second row10. Flyhalf11. Closed flanker12. Open flanker13. Hooker14. Loosehead prop15. Second row

Fourth Place – France

1. Scrumhalf2. Outside center3. Flyhalf4. 8 man5. Fullback6. Second row7. Wing8. Wing9. Inside center10. Open flanker11. Closed flanker12. Second row13. Hooker14. Loosehead prop15. Tighthead prop

Future Direction• More data• RWC 2011• Difference in optimal cooperation?

• Power- Would algorithm have

forecasted the All Blacks’ victory?

Questions

For more: rugbyquant.tumblr.com